1. Technical Field
This invention relates to room temperature fast-curable compositions comprising saturated hydrocarbon polymers as a base polymer, and more particularly, to room temperature fast-curable compositions of the condensation cure type having improved fast-cure and deep-cure capabilities and good water resistance, and double-glazed glass panes using the compositions as a sealant.
2. Background Art
Elastomeric sealing materials are now on widespread use in buildings, vehicles and the like. Sealing materials are used for the purpose of establishing a water or air-tight seal between various members by filling joints or gaps therebetween. It is thus requisite that once applied to joints, window frames or the like, sealing materials cure fast and firmly adhere to various substrates of inorganic materials such as glass, ceramics, metals, cement and mortar and organic materials such as plastics.
For room temperature fast-curable saturated hydrocarbon polymers, a primer composition and a bonding method intended to improve their adhesion are proposed in JP-A 11-209701, but no innovative techniques addressing their cure speed are known. Intending to improve the cure of RTV organopolysiloxane compositions, the inventors previously made research works under the background described below.
Room temperature fast-curable organopolysiloxane compositions of the condensation cure type known in the prior art include one-package compositions in which the amount of a crosslinker is minimized to increase the rate of crosslinking by hydrolysis and two-package compositions in which a crosslinker and a curing agent are separately packed. However, the one-package composition is not regarded as fast-curable because a high speed is available only for curing from the surface and a certain period of time is required for deep curing. The two-package composition is relatively good in deep curing, but is cumbersome to handle because the mixing ratio of two parts is not 1:1, and is thus not compliant with an automatic mixer/dispenser. The amounts of crosslinker and curing agent added must be strictly determined or water must be added as a deep curing agent before the composition can be completely cured to depths. On the other hand, organopolysiloxane compositions of the addition cure type are efficient to work because the mixing ratio of two parts is 1:1, but a heating oven is necessary for curing. In addition, the working environment is restricted since the curing catalysts are poisoned in the presence of addition poisons.
The inventors proposed in JP-A 5-279570 a room temperature fast-curable composition that solved the above-discussed problems. This composition comprises a diorganopolysiloxane or polyoxyalkylene polymer capped with a hydrolyzable silyl group at either end of a molecular chain, an organic compound having at least one carbonyl (C═O) group in a molecule and an organic compound having at least one NH2 group in a molecule, wherein fast-cure and deep-cure capabilities at room temperature are improved by utilizing water formed as by-product by ketimine-forming reaction between C═O and NH2 groups by way of dehydrating condensation. The inventors also proposed in JP-A 2001-303024 to apply the above technology to a room temperature fast-curable saturated hydrocarbon polymer composition.
Continuing the research, however, the inventors found that despite favorable fast-cure and deep-cure capabilities, these compositions have problems with respect to water resistance, typically adhesion in the presence of water and electrical properties after water immersion. Thus the application of these compositions is strictly limited.
It was believed that primary amines left in the cured compositions contribute largely to the above-mentioned decline of water resistance. To solve the problem, the inventors attempted to add an α,β-unsaturated carbonyl compound to the composition for converting a primary amine in the cured composition to a secondary amine, thereby improving water resistance. Adhesion in the presence of water is surely improved, but electrical properties after water immersion still remain problematic, imposing a limit on the application of the composition.